Meg: Not as a Mountain Cur. She has, to the best of my knowledge, never been evaluated as a hunting dog. If someone were considering trying to breed for the ideal family pet dog, she'd be more interesting. I wouldn't say yes as she is; whether her dog issues (reactivity, never actually been aggressive) were in part due to her early life (among other things, I know for a fact she shared a crate - not a kennel, but a crate - with another adult female for quite a while in rescue), or if they could have been prevented - I don't know.
Beyond the dog issue, she's an incredibly ideal pet for most of America. She's a nice medium size, wash and wear coat. She is as close to bombproof as any dog I know with humans of all shapes and sizes. She is happy to go out and be active, but has always handled being home in the house easily. I think she could do just fine as dog who went out in the yard a few times a day. She's got an iron stomach, and has never once had a health issue in the seven years I've owned her. She's too 'soft' for an ideal sport dog, but I think that can be a good trait in a pet.
Gusto: He's too young to really say - but quite likely as part of a sport dog program. His weaknesses would mainly be his size (a bit over the 16" cut-off that I know matters in agility, and which I think is also a big cut-off in flyball) and not quite enough handler focus - which could be a training issue or not.
He's incredibly well built. He's light on his feet without being "flimsy". He's got nicely balanced play/prey/food drives, and can swap from one to the other as a reward and back again. He might be a little soft for some handlers; perhaps my judgement is tainted by having come from Meg! He is softer than I thought when I first was working with him. He needs more work physically and mentally than an ideal pet, but settles well in the house with his current schedule. His dog skills are some of the best I've ever seen. Zero reactivity, happy to play with dogs who want to play, but very respectful of dogs who don't. He isn't outgoing or social with people outside his few favorites, but doesn't display any aggression at all. So far, he's proving to be a nice agility dog, although it is way too soon to really know.
In this hypothetical world, he's one I'd keep an eye on for another year or so and then make a final judgement.